Infant anesthetic machine



June 23, 1959 5, PENTECOST 2,891,542

INFANT ANESTHETIC MACHINE Filed Oct. 25, 1956 FIG-.3

INVENTOR. F3404 RF/YTECOS 7' A T 70 Emma United States Patent INFANTANESTHETIC MACHINE Paul S. Pentecost, San Diego, Calif.

Application October 25, 1956, Serial No. 618,260

4 Claims. (Cl. 128-188) My invention comprises an anesthesior and morespecifically a device for giving anesthetic to extremely young infants.

In administering anesthetic to extremely small infants, there is oneserious difliculty and danger. The tidal volume (number of cc. of gasinhaled or exhaled during normal breathing) of an infant may be verysmall (9 to 17 cc.). The mechanical dead space may be several times thisvolume. As a result, the infant rebreathes gases from this mechanicaldead space. The carbondioxide content of the gases increases, the oxygencontent diminishesleading to respiratory acidosis and hyoxiarespectively.

It is, therefore, the purpose of my invention to reduce the mechanicaldead space to as small a volume as possible (7.5 cc.).

It is another object of my invention to provide an anesthesior whichprevents accumulation of exhaled gases in the mechanical dead space nomatter the size of the patient upon which the machine is used.

Other advantages of my invention will be apparent from the followingdisclosure of the preferred embodiments thereof.

In the drawings:

Figure 1 is an elevation of my anesthesior.

Figure 2 is a schematic view in cross section of the valve arrangements.

An anesthesior constructed in accordance with my invention has an inlet1, for the admission of anesthetic agents and oxygen. From the inlet 1,the gases pass through a venturi nozzle 2, and blow into a venturi tube3, then through the passage 4, past a flutter valve 5 and into thechamber 6, through outlet 7, connected to an endotracheal tube to thepatient.

During the exhalation cycle, the gases pass from the endotracheal tubeinto the chamber 6, through flutter valve 8, through the passage 9,through soda lime canister 10, through soda lime 11 where carbon dioxideis removed. From the canister 10, the gases pass into tube 12. Tube 13,which is the entraining tube connected to the venturi tube, extendsthrough tube 16 into tube 12, the exhalation side of the system. Thegases which enter through inlet 1, venturi nozzle 2 into the venturitube 3 create negative pressure in tube 13. The negative pressure thusproduced pullls the exhaled gases from the chamber 6, thus preventingaccumulation of carbondioxide in this ordinarily dead space. From tube12 part of the gases enter the entraining tube 13, part flows throughtube 16, around tube 13 into tube 4. Part continues on into rebreathingbag 15 and the excess blows out exhalation valve 14.

In prior anesthesiors for infants, the chamber 6 comprises a mechanicaldead space. The volume of this ice 2 chamber 6 exceeded the tidal volumeof the infant. As a result, the infant rebreathes the gases. As aresult,

the CO accumulation caused respiratory acidoses. Also, the partialpressure of oxygen was gradually reduced, resulting in partial, if notcomplete, asphyxia over a period of time.

The rebreathing bag has a tail pipe 17, which can be connected by meansof rubber tubing to a pressure manometer. Thus, a careful check can bemade continuously of positive pressure in the anesthesior.

I claim:

1. In an anesthetic machine for infant patients, a gas inlet, a venturiconnected to said inlet, a chamber having a volume smaller than thetidal volume of the infant patient, a passage from said venturi to saidchamber, an outlet from said chamber to means for delivery to a patient,a backflow preventing valve between said chamber and said passage, acanister to hold carbon dioxide removing chemicals, a passage from saidchamber to said canister, a backfiow preventing valve between saidcanister and said chamber, a breathing bag, a tube connecting saidcanister and said breathing bag, and a passage to port gases from saidtube through said venturi.

2. An anesthetic machine for use with infant patients comprising achamber, said chamber having means to connect a delivery device to saidpatient, means for porting an anesthetic gas to said chamber, a venturiin said means, a valve between said means and said chamber to preventbackflow, exhaust means for porting the exhaust gases from said chamber,a valve in said exhaust means to prevent backfiow, means connecting saidexhaust means with said venturi whereby circulation is maintained insaid exhaust means, said chamber having a volume smaller than the tidalvolume of the infant patient.

3. An anesthetic machine for use with infant patients comprising achamber, said chamber having means to connect a delivery device to saidpatient, means for porting an anesthetic gas to said chamber, a venturiin said means, a valve between said means and said chamber to preventbackflow, exhaust means for porting the exhaust gases from said chamber,a valve in said exhaust means to prevent backfiow, means connecting saidex haust means with said venturi whereby circulation is maintained insaid exhaust means, said chamber having a volume of 7.5 cc.

4. In an anesthetic machine for infant patients, a gas inlet, a venturiconnected to said inlet, a chamber having a volume of 7.5 cc., a passagefrom said venturi to said chamber, an outlet from said chamber to meansfor delivery to a patient, a backflow preventing valve between saidchamber and said passage, a canister to hold carbon dioxide removingchemicals, a passage from said chamber to said canister, a backfiowpreventing valve between said canister and said chamber, a breathingbag, a tube connecting said canister and said breathing bag, and apassage to port gases from said tube through said venturi.

References Cited in the file of this patent UNITED STATES PATENTS2,216,183 Connell Oct. 1, 1940 FOREIGN PATENTS 429,276 Great Britain May28, 1935 1,068,330 France Feb. 3, 1954

